Gate size dependence of the radiation-produced changes in threshold voltage, mobility, and interface state density in bulk CMOS

It has been observed that radiation-induced threshold voltage shifts, interface trap densities, and channel mobility reductions are dependent on the drawn or coded geometrical sizes of transistors in one radiation-hardened VLSI CMOS technology. In another technology, no such dependencies were found. The authors suggest physical mechanisms responsible for the observed size dependencies, and warn that large-area transistors and capacitors for total dose evaluations may not always be suitable. Stress measurements indicate that the radiation-induced changes are correlated with higher tensile stress levels.>